The present invention relates to a tool for a sewer robot for sealing-off the connection of a secondary sewer (36) to a main sewer (1), having a sheathing plate (34) which has an outlet opening (39) for a spackling composition, to which outlet opening a pressure line (12) for the forcing-in of a sealing composition can be connected.
From EP-C-396 696 it is known to seal off a subsidiary sewer leading into a non-man-size main sewer between the mouth of the former and the place of leakage by means of an inflated balloon. After the balloon has been put properly in place, the mouth of the secondary sewer is covered and closed off with a sheathing plate which is curved corresponding to the diameter of the main sewer, whereupon the hollow space between the sheathing plate and the balloon is filled under pressure with a pasty flowable sealing composition. Thereupon, a hole corresponding to the inside diameter of the secondary sewer is cut by means of a cutter in the solid body which has thus been formed in the region of the mouth of the secondary sewer.
This procedure has various disadvantages. On the one hand, after the positioning of the balloon, the robot must be moved out of the main sewer and provided with a sheathing tool and then moved back again to the point of repair. Another disadvantage is that the balloon can be used only once, since it is destroyed in this process. Another disadvantage is that, after the hardening of the sealing composition, it is difficult for the operator again to find the center of the mouth of the secondary sewer in order to position the cutter head axially to the secondary sewer and advance it therein. Furthermore, in this process, a comparatively large amount of sealing composition must be pumped to the place which is to be repaired and milled out after it has hardened, which consumes a lot of material and time and increases the wear of the material and the tool.